Cathode ray tube



April 19, 1938. K. SCHLESINGER CATHODE RAY TUBE Filed Nov. 26. 1934 2Sheets-Sheet l 7/? 126/? foe: MET/m? April 19', 1938.

GATHODE RAY TUBE Filed Nov. 26, 1954 2 Sheets-Sheet 2 K. SCHLESINGER,613

Patented Apr. 19, 1938 UNITED STATES PATENT OFFICE Application November26, 1934, Serial No. 754,710 In Germany November 27, 1933 16 Claims.

This invention relates to electron tubes for amplifying and likepurposes.

The invention will be best understood with reference to the accompanyingdrawings of which Fig. 1 is a perspective view of the electrode systemof an electron tube acting on the so-called transverse field principleand designed according to the invention, whereas Fig. 2 is a sectionalview of the same system, both said figures showing some essentialcircuit elements too.

Fig. 3 shows a special embodiment of partanodes of the tube in planview, while in Fig. 4 there is illustrated an additional feature of theinvention consisting in the cascade connection of a plurality of tubesaccording to the invention.

In particular referring to Fig. l the arrangement comprises a straightcathode filament l of, say, 40 mm. in length, which is arranged within asheet metal box-like structure 2. In front of the sheet metal structure2 there is situated a. sectional anode 3 having a wide aperture, behindthis anode a further box 4, and behind the latter an anode having a verynarrow aperture 5. The potentials hereinafter recited are to beunderstood relatively to cathode potential as zero potential. If the box2 and the box 4 are connected to a potential not considerably differentfrom zero, or with suitable dimensioning, are connected with zeropotential itself, and the anodes 3 and 5 are on the other hand connectedwith a potential of 200 volts, it is possible to cause practically allof the electrons emitted by l to pass through the diaphragm aperture of5 with a. comparatively small angle of dispersion and reach thedeflecting space situated behind the same. Naturally in accordance withthe invention all of the stated electrode potential may also beregulated separately. In the deflecting space there are situated the twodeflecting plates 6 and I which are, for example, approximately 40 mm.high. Behind these there is located a box shaped electrode 8, and thenan additional box shaped electrode 9, and finally two anodes l0 and H.The latter are shown in plan view in Fig. 3. In the practical form ofembodiment of the tubes all electrodes are conveniently closed oil bymetal parts towards the front and the rear, so that the entire tube isgiven a box-like structure, in such a manner that the electronic path iscompletely screened off towards the outside.

The tube according to the invention is preferably of the high vacuumtype.

The tube may be connected as follows:

An anode battery l2 of approximately 200 volts is connected with itspositive pole not only with the preliminary anodes 3 and 5, but alsowith the upper box 9, and with its negative pole with 5 the filament Iand the concentration electrodes 2 and 4 connected therewith. A partpotential tapped from this anode battery is linked up "with the lowerbox electrode 8. Preferably this component potential is earthedexternally, directly earthed (earth l3). One of the deflecting plates,for example the plate 6, is connected with the source ll of the voltageto be amplified, the other pole of which source is practically alwaysearthed. The plate 7, according to the invention, is earthed over apotentiometer l5 at a tapping l6, whilst the free pole of thepotentiometer I5 is connected with the anode l0 through the medium ofthe blocking condenser Ill. The anode Ill receives a bias via theresistance l9, which should be high as compared with IS in respect ofall frequencies employed. The anode II is earthed as regards alternatingcurrent over a working resistance 26 and condenser I1. The two anodesreceive a d. c. bias from the battery l2, it being with suitabledimensioning also possible to operate the tube with a bias whichcoincides with the earth potential l3. Under certain circumstances thismay be accomplished by the provision of a coarse-mesh net 9a in front ofthe anode connected with 9, or by increase of the length of 9, wherebythere is certainly obtained a wider electronic image, but on the otherhand a greater sensitiveness of deflection in mm. per volt. In thelatter case the condenser l8 and the feeding resistance l9 and thecondenser I'I may also be dispensed with. The amplified potential istaken through the medium of a block 20.

The operation of an arrangement of this nature is as follows:

The aperture of 5 onto which an intense electron stream is projected bymeans of the concentrating device I, 2, 3, 4, as described above, isreproduced sharply on the plane of the anodes l0 and II. Thisreproduction is obtained by the fact that the lower system: deflectingplates 6 and i and guard screen 8 are connected in common with a lesshigh positive bias than the upper system 9 and possibly l0 and II. Inconsequence there are formed at the line of intersection between 9 and 8potential lines of the form as shown in broken lines and designated 2|in Fig. 2. This combination already described by the applicant on aprevious occasion provides .55'

an electrostatic electron-optical reproduction on a scale which, as inthe optical art, may be calculated from the distance between the objectto be reproduced (i. e. the aperture in 5) and the line of intersectionof 8-9 on the one hand and the distance between that line ofintersection and the image (in the plane Ill-H) on the other hand. Inthe stated tube the first mentioned distance is approximately 50 mm.,and the ring 8 approximately 10 mm. and the upper guard ring 9approximately 20 mm. high, so that the image is approximately half aswide as the aperture of 5, and in practice with an aperture .5 mm. inwidth merely an electronic image of .25 mm. in width is projected on tothe anodes l0 and II. A filling of gas is unnecessary. The oscillatingvoltage II to be amplified causes this electronic image to oscillatelaterally, and thus to sweep over the line of separation shown in Figs.1 and 3 between the two part-anodes I0 and II. It is possible,therefore, to obtain at the anode II a potential corresponding in itsphase to the voltage l4 and being amplified in relation to I by a factorwhich is proportional to the slope tan a (Fig. 3). The lower ring 8 hasthe object of screening off the electrostatic refractive edge 2| againstthe variable field between 6 and I. The diameters of 8 and 9 are furtherselected to be so much larger than the maximum extent of movement on thepart of the cathode ray that the reproduction remains uniformly sharpeven at the edge.

In accordance with the invention, the distance of the object to beelectron optically reproduced from the reproducing lens may be selectedto be relatively large, and the two anodes l0 and I I may then beconnected with earth.

The measure according to the invention enables difierent extremelyeffective connections to be performed.

In order to increase the amplification beyond the product of workingresistance 26 and steepness it is possible, for example, to employ thefollowing galvanic back-coupling according to the invention: The circuitanode I0 is, as regards alternating currents, connected over l8 with theplate I, provision being made for ad- ;lustability of the degree of thiscoupling by the tapping ii. In this manner, as quite readily apparent,the oscillation amplitude is considerably increased.

The degree of back-coupling may be increased to such an extent inaccordance with the invention that the ray is capable of assuming merelytwo positions of deflection, which remain stable. Since the ray isthrown suddenly from the one to the other position as soon as thepotential ll exceeds a certain amount, an arrangement of this nature isvery suitable as a tilting relay dependent on a threshold value, and maywith advantage be employed in all circuits known for this purpose, forexample, as a substitute for the Turner callirotron, which is anoscillator comprising two valves, in which a negative resistance effectis obtained in the anode circuit of the second valve, and in which thegrid of the second valve is connected to the anode circuit of the firstvalve and the anode circuit of the second valve connected to the gridcircuit of the first valve. A description of this device is for instanceto be found in Scott-Taggarts book on Thermionic Tubes", second edition,published from the ofiices of The Wireless World" on page 416.

An additional feature of the invention consists in the cascadeconnection of a plurality of these tubes (Fig. 4). For simplicitys sakethere are shown of these tubes merely the diaphragms 5, the deflectingplates 6 and I and the two anodes l0 and H. The first tube is operatedby the potential source I4 in the back-coupling connection abovedescribed increasing the amplification aperiodically. Amplifiedpotential fluctuations are then obtained at the anodes III and H, thoseobtained at ll having the same phase .as, those obtained at l0 having aphase reversed in relation to, the input voltage fluctuations.

The output of the first tube is coupled to the input of the second one.This coupling may be effected in single phase by providing only oneconnection, such as the wire 22, between the first and second tubes.According to a further feature of the invention, however, the saidcoupling is preferably effected by a push-pull connection employing twowires 22 and 23. The sensitivity of pushpull cathode ray deflection is,other data being equal, twice the sensitivity of single phase cathoderay deflection. The amplification per stage obtained by the push-pullcoupling is accordingly doubled in relation to that obtained by singlephase coupling. The output potentials may be taken from the anodes l0and I I of the final tube in opposite phases, and under certaincircumstances, therefore, may be doubled by the use of a counter-cadencetransformer 24, even if this possesses the transformation ratio 1.Naturally the sensitiveness of the second tube may also be increased bythe use of 2. preferably aperiodic back-coupling in the same manner asdescribed in connection with the first tube. This is particularlyadvisable in those cases in which, due to wide frequency bands, the useof transformers is made diificult, for example in certain amplifiercircuits for teevision purposes.

The circuit shown in Fig. 4 may, since it is possible in accordance withthe invention to avoid block condensers in the train of the lines 22,23, be employed as an effective d. c. amplifier. The condition inquestion may be fulfilled either by so dimensioning the distance of theanodes from the other parts of the electrode system in the tubes inFigs. 1 and 2 that the anodes ill and II may be directly connected withearth, or this condition may also be fulfilled by correspondinglyincreasing from stage to stage the battery potential of the tubes. Thegreat advantage of d. c. amplifiers of this nature as compared withknown arrangements is to be regarded in the fact that variations in theoperating potential in the case of transverse-field tubes have no effecton the position of the electronic images but affect merely theirintensity, and that it is, therefore, out of the question that smallvariations of this nature in the preliminary stage should be able todisplace unfavourably the working point in the final tube.

I claim:

1. An electron tube comprising means including a cathode for producing abundle of electrons, at least one anode structure comprising at leastone equipotential element, electron optical means comprising a pluralityof electrodes consecutively mounted along the direction from saidcathode to said anode structure for producing in the space between saidcathode and said anode structure an electron-optical lens field forforming said bundle into a sharp electron image in the plane of saidanode structure, a wire net mounted between said anode structure and theadjacent one of said electrodes, and connected with the last mentionedelectrode, further electron-optical means mounted more remote from saidanode structure than the first said electron-optical means forsubstantially parallelizing said bundle, and electron deflecting meansmounted between said cathode and said anode structure for deflectingsaid bundle of electrons to a variable degree to cause the percentage ofelectrons impinging on any of said equipotential elements to be variablein dependence on the variations in the degree to which said bundle'isdeflected.

2. An electron tube for producing electrically influenced currents,comprising means including a cathode for producing a bundle ofelectrons, an anode structure comprising at least one equipotentialelement, electron optical means mounted between said cathode and saidanode structure for producing an electron optical lens field for formingsaid bundle into a sharp electron image in the plane of said anodestructure, further electron optical means, mounted more remote from saidanode structure than the first said electron optical means, forsubstantially parallelizing said bundle, and electron deflecting meansmounted between said cathode and said anode structure for deflectingsaid bundle of electrons to a variable degree to cause the percentage ofelectrons impinging on any of said equipotential elements to be variablein dependence on the variations in the degree to which said bundle isdeflected.

3. An electron tube for producing electrically influenced currents,comprising means including a cathode having an emissive surface thewidth of which is small as compared with its length, for producing abundle of electrons, an anode structure cc .nprising at least oneequipotential element, el ctron optical means mounted between saidcathade and said anodestructure for producing an electron optical lensfield for forming said bundle into a sharp electron image in the planeof said anode structure, further electron optical means, mounted moreremote from said anode structure than the first said electron opticalmeans, for substantially parallelizing said bundle, and electrondeflecting means mounted between said cathode and said anode structurefor deflecting said bundle of electrons to a variable degree in adirection forming right angles with the main direction of said emissivesurfaceto cause the percentage of electrons impinging on any of saidequipotential elements to be variable in dependence on the variations inthe degree to which said bundle is deflected.

4. An electron tube for producing electrically influenced currents,comprising means including a cathode having an emissive surface thewidth of which is small as compared with its length for producing abundle of electrons, an anode structure comprising at least oneequipotential element having an edge which is sloped with respect to themain direction of said emissive surface, electron optical means mountedbetween said cathode and said anode structure for producing an electronoptical lens field for forming said bundle into a sharp electron imagein the plane of said anode structure, further electron optical means,mounted more remote from said anode structure than the first saidelectron optical means, for substantially parallelizing said bundle, andelectron deflecting means mounted between said cathode and said anodestructure for deflecting said bundle of electrons to a variable degreein a direction forming right angles with the main direction of saidemissive surface to cause the percentage of electrons impinging on anyof said equipotential elements to be variable in dependence on thevariations in the degree to which said bundle is deflected.

'5. An electron tube for producing electrically influenced currents,comprising means including a cathode having an emissive surface thewidth of which is small as compared with its length, for producing abundle of electrons, an anode structure formed by a plate-shaped elementmounted at right angles to the normal path of said bundle and separatedinto two equipotential elements insulated from each other by a slotdisposed at an acute angle with respect to the main direction of saidemissive surface, electron optical means mounted between said cathodeand said anode structure for producing an electron optical lens fieldfor forming said bundle into a sharp electron image in the plane of saidanode structure, further electron optical means mounted more remote fromsaid anode structure than the first said electron optical means forsubstantially parallelizing said bundle, and electron deflecting meansmounted between said cathode and said anode structure for deflectingsaid bundle of electrons to a variable degree in a direction formingright'angles with the main direction of said emissive surface to causethe percentage of electrons impinging in any of said equipotentialelements to be variable in dependence on the variations in the degree towhich said bundle is deflected.

6. An electron tube for producing electrically influenced currents,comprising means including a cathode for producing a bundle ofelectrons, an anode structure comprising at least one equipotentialelement, a diaphragm having an aperture positioned in the path of saidbundle between said cathode and said anode structure, electron opticalmeans mounted between said diaphragm and said anode structure forproducing an electron optical lens fleld for forming said bundle into asharp electron image of said diaphragm aperture in the plane of saidanode structure, further electron optical means, mounted more remotefrom said anode structure than said diaphragm, for substantiallyparallelizing said bundle, and electron deflecting means mounted betweensaid diaphragm and said anode structure for deflecting said bundle ofelectrons to a variable degree to cause the percentage of electronsimpinging on any of said equipotential elements to be variable independence on the variations in the degree to which said bundle isdeflected.

7. An electron tube for producing electrically influenced currents,comprising means including a cathode having an emissive surfacethe widthof which is small as compared with its length for producing a bundle ofelectrons, an anode structure comprising at least one equipotentialelement, a diaphragm having a very narrow aperture similar in shape anddisposed in parallel to said emissive surface positioned in the path ofsaid bundle between said cathode and said anode structure, electronoptical means mounted between said diaphragm and said anode structurefor producing an electron optical lens fleld for forming said bundleinto a sharp electron image of said diaphragm aperture in the plane ofsaid anode structure, further electron optical means mounted more remotefrom said anode structure than said diaphragm, for substantiallyparallelizing said bundle, and electron deflecting means mounted-betweensaid diaphragm and said anode structure for deflecting said bundle oi.electrons elements to be variable in dependence on the variations in thedegree to which said bundle is deflected.

8. The invention set forth in claim 2 and wherein the first structuralelement, counting from the I cathode side, which is mounted between saidcathode and said anode structure, is a section anode.

9. The invention set forth in claim 2, and wherein said further electronoptical means comprise two plane rectangular metal sheets mounted inparallel to each other and to the normal path of said bundle andflanking said bundle from opposite sides thereof.

10. The invention set forth in claim 2, and wherein said furtherelectron optical means comprise two plane rectangular metal sheetsmounted in parallel to each other and to the normal path of said bundleand fianking said bundle from opposite sides thereof, and two furtherplane rectangular metal sheets supplementing the two first said sheetsto form a box-like structure.

11. The invention set forth in claim 2, and wherein the first saidelectron optical means comprise two pairs of plane rectangular metalsheets mounted in parallel to each other and to the normal path of saidbundle, the sheets of each of said pair flanking said bundle fromopposite sides thereof, said two pairs being mounted to follow one onthe other in the direction of the normal path of said bundle and beingadapted to have different potentials impressed thereo 12. The inventionset forth in claim 2, and wherein the first said electron optical meanscomprise two pairs of plane rectangular metal sheets mounted in parallelto each other and to the normal path of said bundle, the sheets of eachof said pairs flanking said bundle from opposite sides thereof, said twopairs being mounted to follow one on the other in the direction of thenormal path of said bundle and being adapted to have differentpotentials impressed thereon, and two further pairs of plane rectangularmetal sheets, each of said further pairs supplementing one of the firstsaid pairs to form a box-like structure.

13. An electron tube for producing electrically influenced currents,more particularly a high vacuum tube, comprising means including acathode for producing a bundle of electrons, an anode structurecomprising at least one equipotential element, electron optical meansmounted between said cathode and said anode structure for producing anelectron optical lens field for forming said bundle into a sharpelectron image in the plane of said anode structure, further electronoptical means, mounted more remote from said anode structure than thefirst said electron optical means, for substantially parallelizing saidbundle, and electron deflecting means mounted between said cathode andthe first said electron optical means for deflecting said bundle ofelectrons to a variable degreeto cause the percentage of electronsimpinging on any of said equipotentlal elements to be variable independence on the variations in the degree to which said bundle isdeflected.

14. The invention set forth in claim 2, wherein said deflecting meansare deflecting plates, and wherein the first said electron optical meanscomprise two pairs of plane rectangular metal sheets mounted in parallelto each other and to the normal path of said bundle, the sheets of eachof said pairs flanking said bundle from opposite sides thereof, said twopairs being mounted to follow one on the other in the direction of thenormal path of said bundle and being adapted to have differentpotentials impressed thereon.

15. The invention set forth in claim 2, wherein said deflecting meansare deflecting plates, mounted more remote from said anode structurethan the first said electron optical means, wherein the first saidelectron optical means comprise two pairs of plane rectangular metalsheets mounted in parallel to each other and to the normal path of saidbundle, the sheets of each of said pairs flanking said bundle fromopposite sides thereof, said two pairs being mounted to follow one onthe other'in the direction of the normal path of saidburidle and beingadapted to have different potentials impressed thereon, and wherein thatone of said pairs mounted never said deflecting plates is generouslydimensioned in the direction parallel to the normal path of said bundle,so that this last mentioned pair screens the lens field produced by thefirst said electron optical means from said deflecting plates.

16. The invention set forth in claim 2, wherein said deflecting meansare deflecting plates, wherein the first said electron optical meanscomprise two pairs of plane rectangular metal sheets mounted in parallelto each other and to the normal path of said bundle, the sheets of eachof said pairs flanking said bundle from opposite sides thereof, said twopairs being mounted to follow one on the other in the direction of thenormal path of said bundle and being adapted to have differentpotentials impressed thereon, and two further pairs of plane rectangularmetal sheets, each of said further pairs supplementing one of the firstsaid pairs to form a box-like structure, wherein said further electronoptical means comprise "a pair of plane rectangular metal sheets mountedin parallel to each other and to the normal path of said bundle andflanking said bundle from opposite sides thereof, and yet a further pairof plane rectangular metal sheets supplementing the aforementioned pairincorporated in said further electron optical means to form a box-likestructure, and wherein said deflecting plates are likewise provided withsupplementary metal members to give them a box-like structure as well,so that the complete path of said bundle is electro-statically screenedtowards the outside.

KURT SCI-ILESINGER.

